Computerworld - Windows XP may be the last Microsoft operating system to hold a majority share, according to data from Web metrics company Net Applications.

At its peak, Windows XP powered more than eight out of every 10 computers worldwide. In November 2007, the earliest month for which Computerworld has Net Applications' data, XP accounted for 83.6% of all operating systems.

Although Windows XP's share has gradually declined since then, it still enjoys a slight majority: Last month, XP owned a 52.4% share.

The long lag time between Windows XP's release in 2001 and Vista's debut in late 2006 -- combined with Vista's stumble in the marketplace -- are the factors usually cited to explain XP's large-scale and long-term dominance.

Both conditions could be reproduced -- Microsoft might face future failures like Vista -- but the one least likely to happen again is the five-year gap between upgrades.

That's because Microsoft has taken to a three-year development cycle. Even though the company has been mum about a ship date for Windows 8, the operating system it showed off last week, most experts have pegged its release to the fall of 2012, or three years after Windows 7's launch.

With a regular cadence between upgrades, it's unlikely that any one edition of Windows will be able to duplicate XP's supremacy.